DIY: BenDoser

  • Thread starter bentripin
  • Start date
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The BenDoser v1.0

So easy even a caveman could do it..

Do it your self simple Doser, this device will measure out a pre-determined amount of solution (min ~5ml/max ~70ml) and then dispence it into your nutrient tank at programmed intervals. Its very cheap, can be built for ~$60 or less and is gravity operated.. no pumps needed!

This is just the doser, it can be hooked up to a controller such as the Milwalkee SMS-122 for ~$110 or a simple timer if your brave and/or cheap ($15-25)..
It wont overdose as long as you set it up properly, the dosage amount is set by raising or lowering the float valve in the measuring syringe.. Once the float is set to your desired position it will dispence the same dose every time it is triggered.

Here is a video of it in action:
Here is the basics..

Minimum of what you'll need:
  • Container Full of Solution (ie, pH Down) with a drain at bottom.
  • Measuring Syringe
  • 12v Float Switch
  • Two NC 12v Solenoid Valves, I used EHCOTECH BBTF-CD-12VDC
  • 1/4" Tubing
  • 12v SPDT Relay

How it works:
  • 12v Power supply is plugged in, top valve opens.
  • Gravity Drains solution into Syringe
  • Fluid reaches float & triggers/locks relay
  • Top valve closes, Bottom Valve Opens
  • Solution is drained into the tank
Break the relay coil with a momentary switch to give another dose (optional)

attached is the wiring diagram, if your electrically inclined this should be simple.

Coming soon is Step by Step Instructions!

Diy bendoser
Bendoser wiring
Diy bendoser 3
Diy bendoser 4


pretty cool... That is one bad ass solution for real cheap.

I've played with some dosers and automation. I hope you don't mind me posting a different solution, even though it's slightly more expensive... here is a write up I did a while ago.

I figured I would be stuck with 3k in costs just for a good PH controller ()

After some research, I have found this alternative for any grow... no more worries about ph fluctuations while you're out at the movies with your girl (or man)

Manufactures web site:

Users guide:

Cliff notes on users guide:
Calibrate PH probe.
Set lowest acceptable PH (with small screwdriver)
Set highest acceptable PH ^^^ Same
Connect two pumps... Like these:

to one of the plugs on the back of the PH pinpoint. Run a small air line from the pump to your res and a second line to a gallon of PH UP. Repeat for second plug and run to PH down.

budget $250...


very cool controller, I've been looking for a decent controller for both up & down for when I start automating addbacks I'll need to go up.

got any pics of yer setup?


Not of the the dozers setup, My journals pretty much have the pics of my current rooms.

I'm not currently using the dozers as I'm feeding and PH'ing by hand.

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